The invention relates to a security feature for securing value documents, comprising a chemically unstable inorganic feature substance and a substance that stabilizes the feature substance. The invention further relates to a value document having the security feature.
Numerous possibilities for protecting unstable inorganic feature substances are described in the prior art. From DE 10 2004 063 217 A1 and DE 10 2009 056 634 A1 the coating of the unstable inorganic feature substance with a stabilizing envelope is known. However, the additional method step of enveloping is technically complex and cannot be applied to all feature substances. For example, no protection for feature substances that are destroyed by the coating process can be obtained in this way.
Furthermore, feature substances based on unstable inorganic luminescent substances and their protection by three-dimensionally crosslinked adhesive layers in value documents are known for example from the document DE 10 2014 011 383A1. In this case, however, the protection also takes place by means of a type of envelope.
It is the object of the invention to make available an improved security feature for securing value documents and a value document supplied with such a security feature.
This object is achieved by the combinations of features defined in the independent claims. Preferred embodiments are the subject matter of the dependent claims.